This invention is related to a ground advance shoring system and the construction method using such a system. This invention is primarily utilized in the construction of elevated roads or bridges. By utilizing the method and system according to this invention, construction costs can be significantly reduced and the work period can be shortened along with improved construction efficacy.
The conventional construction systems for elevated roads or bridges can be generally categorized into a stationary shoring system and an advancing shoring system. To facilitate better understanding of the technical features and advantages of this invention, the above two conventional construction methods are summarized as follows.
The conventional stationary shoring system, as illustrated in FIGS. 1 and 2, generally includes stationary supporting frames 11 set up on the ground 10, and molding plates 16 along with other facilities installed on the supporting frames 11 for subsequent casting of bridge concrete 15. The conventional stationary shoring construction method includes ground conditioning and pavement of one or several layers of gravel (not shown) thereon. Concrete blocks 13 are then covered on the gravel. Next, a plurality of supporting frame units 14, as illustrated in FIG. 3, are connected by screws and/or connection rods to form the complete supporting frames 11 on the concrete blocks 13 as shown in FIGS. 1 and 2. After completing the installation of the supporting frames 11, additional supporting facility, such as steel H-beams 12 and wooden corners (not shown) etc., are installed on the supporting frames 11 and the molding plates 16 are installed on the supporting facility for subsequent pouring of the bridge concrete 15.
The above conventional stationary shoring construction method involves many disadvantages. Firstly, since the loading capacity for a single supporting frame unit 14 is very limited, the overall supporting frames 11 must be connected as a dense supporting network by a large number of the supporting frame units 14 so as to evenly distribute the weights of the supporting frames 11 themselves and the bridge concrete 15 over each of the supporting frame units 14 for safe and sufficient support. Accordingly, the conventional stationary shoring construction method requires a considerable a mount of materials for the supporting frames. Secondly, each of the supporting frame units 14 must be connected by screws, connection rods or other means (not shown) one by one and thus, the installation or dismantling thereof is thus very time-consuming. In addition, the conventional stationary shoring construction method needs movable or fixed concrete blocks 13 such that the weight of the bridge concrete 15 can be evenly distributed on the ground 10. For the concrete blocks 13 not to be moved, they need to be demolished and shipped away after the completion of the construction. This results in considerable waste of concrete material and requires additional manpower, materials and construction time. For the movable concrete blocks 13, heavy machinery for moving them is necessary and thus, it still requires substantial manpower and working time.
In the conventional stationary shoring construction method, each of the supporting points 17 needs to be leveled prior to the pavement of the steel H-beams 12 over th e supporting frames 11. As can be seen in FIGS. 1 and 2, the amount of supporting points 17 is enormous. Therefore, the time for leveling them is very long. Furthermore, crane truck(s) is/are required to remove and dismantle the supporting frames 11. Here, a xe2x80x9cseries of supporting framesxe2x80x9d means a plurality of the supporting frame units 14 connected in a vertical direction. The supporting frames 11 shown in FIGS. 1 and 2 are usually disconnected horizontally only, but not vertically, so as to save some time and manpower for the dismantling. Each series of the supporting frames is tilted and put on a truck by the crane truck for subsequent construction process of the next span. If the supporting frames 11 are too high, the usual crane truck would not be able to reach them. Accordingly, a heavy crane truck will be necessary which results in additional costs, machinery and manpower along with increased difficulty in operation.
The advancing shoring system is generally illustrated in FIG. 4, characterized in that each of the left and right sides of the concrete post 20 of the bridge has a recess 21. A bracket 22 can be mounted into the recess 21 and a slidable truss 23 is provided on the bracket 22. Steel H-beams 24, molding plates 25 and/or other facilities similar to those utilized in the conventional stationary shoring system can be installed on the truss 23 for the casting of the bridge concrete 26. After completing the casting of each span of the bridge concrete 26, the molding plates 25 will be lowered and separated. The advancing shoring system then employs a driving means (not shown) to move the truss 23 to the next span, as illustrated in FIG. 5. The molding plates 25 will be re-installed again to repeat the casting of the bridge concrete 26. As compared with the conventional stationary shoring system, the advancing shoring system requires less supporting materials. In addition, the manpower and time for installing and dismantling the supporting frames can be eliminated with significant improvement on the construction efficiency. Nevertheless, the advancing shoring system still has some disadvantages. Firstly, the recesses 21 need to be formed on each of the precasted concrete posts 20, as illustrated in FIG. 4, which increases the inconvenience in the construction processes. Secondly, the dimensions and weight of the truss 23, usually made of steel, used in the system are generally enormous, approximately 600-700 tons, to provide sufficient supporting strength. Since the complete weight of the truss 23 must be supported by the concrete post 20, the design of it needs to be changed when this is taken into consideration. Furthermore, the technique of the advancing shoring construction method is more difficult than that of the conventional stationary shoring construction method. Collapse of the supporting facility when moving the system to the next span can happen and thus, extreme caution is definitely required in the advancing shoring construction method. The current costs for an advancing shoring system is generally more than one million U.S. dollars, which is relatively expensive. In addition, at least two crane trucks with more than one hundred ton capacity are required for at least 45 days. Thus, the craning job in the advancing shoring construction method is not only quite difficult but also expensive. For example, if the cost for the crane is US$300 per day, the basic cost for the crane trucks would be 300 (US$/truck)xc3x972 (truck/day)xc3x9745 (days)=US$27,000. Accordingly, if the number of spans for continuous construction is not large enough, that is, the construction length of the elevated road or bridge is not long, the actual costs for the advancing shoring construction method is not necessarily lower than that of the conventional stationary construction method.
It is therefore a primary object of this invention to overcome the above defects of the conventional art. This invention discloses a ground advance shoring system and the construction method using such a system. The system of this invention comprises a railway assembly for being set up on a ground; at least one movable device disposed on the railway assembly for moving thereon, in which the movable device includes a moving platform and a bottom jack provided below the moving platform for lifting and releasing the moving platform; when the bottom jack lifts the moving platform, the movable device is separated from the railway assembly and unable to move along the railway assembly, whereas when the bottom jack releases the moving platform, the movable device engages the railway assembly for moving thereon; a plurality of framework supporting units being vertically stacked on the movable device to form a supporting tower; and a top jack assembly being provided above the supporting tower and a mold supporting frame being provided on the top jack assembly, and a mold plate assembly being set up on the mold supporting frame; wherein the top jack assembly is provided for adjusting longitudinal and traverse gradients of the mold supporting frame.
With respect to the ground advance shoring construction method according to this invention, generally comprises the steps of (a) paving and leveling aggregate on a generally conditioned ground; (b) covering a plurality of lining plates on the aggregate; (c) paving at least one railway on the lining plates; (d) locating at least one movable device on the railway, in which the movable device includes a moving platform and a bottom jack provided below the moving platform, so that the moving platform is lifted away from the railway and supported by the bottom jack when the movable device is moved to a designated position; (e) vertically stacking and securely locking a plurality of framework supporting units on the movable device to form a supporting tower; (f) locating a top jack assembly on the supporting tower and then locating a mold supporting frame on the top jack assembly, in which the top jack assembly is provided for adjusting longitudinal and traverse gradients of the mold supporting frame; and (g) setting up a mold plate assembly on the mold supporting frame.
The set of mold plate assembly is then ready for concrete casting. After the concrete being cured, the mold plate assembly is lowered and separated from the concrete and the bottom jack is released such that the movable device resumes engaging the railways. Then the movable device and the supporting tower thereon is moved to a next designated position, the movable device is lifted and secured by the bottom jack, and the mold plate assembly is again installed for concrete casting.
The ground advance shoring construction method and the utilized system according to this invention involves many advantages. Firstly, as compared with the conventional stationary shoring construction method, the framework supporting unit utilized in this invention has a larger volume than that of the traditional supporting frame unit. Therefore, for supporting structures of identical height, the number of the framework supporting units required in this invention can be considerably reduced as compared with that of the traditional supporting frames and thus, the time for installation thereof can be shortened. Secondly, since the number of the supporting towers of this invention is far less than the number of the conventional supporting frames and the large mold supporting frames are used on top of the supporting towers, the number of supporting points is dramatically reduced in this invention, and so is the time for leveling them. Furthermore, there is no need to dismantle the supporting towers of this invention after completing the concrete casting of each span. The movable device and the supporting tower thereon can be directly moved to the next span by an electric motor, winch or even manually, so as to save time for dismantling and re-assembly of the supporting frames.
As compared with the conventional advancing shoring construction method, it is unnecessary for this invention to reserve recesses on the concrete posts, therefore, no variation regarding the design of the concrete post is required. In addition, the construction techniques utilized in this invention are considered much easier than those of the advancing shoring construction method. The working time, manpower and costs of this invention are also reduced, and no additional training program is required for the workers, as is necessary for the conventional advancing shoring construction method. Specifically, the construction of the supporting facilities of this invention is relatively simple and the cost thereof is obviously less than that of the conventional advancing shoring system.
The structures and characteristics of this invention can be clearly realized by referring to the appended drawings and explanations of the preferred embodiments.